High tension sleeve insulator



Aug. 14, 1934. H. WIRTH 1,969,917

7 HIGH TENSION SLEEVE INSULATOR Filed June 10, 1931 By P fi/forney.

Patented Aug. 14, 1934 UNITED STES PATENT OFFICE HEGH TENSION SLEEVE INSULATOR Switzerland Application June 10, 1931, Serial No. 543,293 In Germany June 17, 1930 1 Claim.

Known high tension sleeve insulators which are filled with semi-fluid, or liquid or fusible dielectric present the following features.

The conductor is led through a cavity enclosed by flanged tubular insulating members and filled with fluid insulating material. In order to prevent partial breakdown of the fluid dielectric with formation of bridges in the electrical field, there are introduced thin-walled tubes of solid insulating material which in normal operation carry only a very small part of the total potential, since, as a rule the dielectric constant of the solid insulating material is much higher than that of the fluid. In order to improve the electrical field there are sometimes fitted in the tubes conducting sheaths. With this form of construction the dimensions are very large as much heavier stresses are experienced at the conductor and the earth electrode than in the remaining part of the dielectric, so that the dielectric is not distributed economically. Calculation made beforehand with regard to such insulators cannot be relied on. Another construction comprises as the active part of the insulator a homogeneous condenser body in oil, the condenser body serving as the insulator proper and the oil charge merely preventing the ingress of moisture. Further, there are known condenser insulators comprising a solid dielectric with an oil-filled gap between two co-axial solid bodies. In this last mentioned construction the function of the oil is merely to provide additional cooling or to prevent ingress of moisture, and its active volume is not comprised within the limits to which the present invention is confined. These constructions are expensive, some on account of the large quantity of material required, and others on account of the expensive nature of the insulating body.

The present invention consists of an insulator comprising the combination of condensers whose dielectrics have diiferent dielectric constants, which condensers are disposed in a body of mobile dielectric material whereby th-ere is obtained a construction of minimum dimensions, with the possibility of calculating with exactitude beforehand, best utilization of the material and greatest certainty of operation with great economy.

The accompanying drawing shows diagrammatically a radial section of an insulator according to the present invention.

1 denotes a conductor of uniform or practically uniform potential; 2 denotes the grounded so electrode or a sheath of uniform or practically uniform potential; 3 denotes conducting linings in, for example, co-axial arrangement, 4 and 5 are dielectrics, the dielectric constant of 5 being higher than that of 4. 6R

If the annular space between 2 and 1 be termed the active volume then the best proportion of the material with the higher dielectric constant is between 5% and of the active volume.

As dielectrics there may be employed:--trans- 7 former oil, semi fluid, plastic masses or mixtures 'of the same, fibrous materials impregnated with oil or resin, ceramic materials etc. For the parts which are to have higher dielectric constants, there may be preferred among the materials mentioned one obtainable by impregnation under vacuum of a solid material with the main filling material, for example, insulating oil. Thereby the dielectric constant of the combination can be altered by varying the content of oil or solid insulating material.

The use of a solid insulating material is preferable for the outermost and innermost portions. The outermost covering 2 is entirely bedded in solid insulating material. The conducting linings may be of metal foil, of open metal work, of semiconducting material or the like. The linings may be formed in a fluid or plastic material of sheet metal cylinders, or the linings may be bedded in thin-walled tubes of solid insulating material. It is possible to form an outer insulating body from solid material of a higher dielectric constant and to use the same as a container.

The invention claimed is:

An insulating bushing comprising an insulating body of solid dielectric containing a plurality of coaxially positioned conducting layers, the concentric space between said body and the conductor containing a fluid dielectric having a plurality of coaxially situated conducting cylinders therein, the said body forming a part of 190 the container for said fluid dielectric.

HEINRICH WIRTH. 

